1. Field of the Invention
The present invention is related to the field of data communications, and more specifically towards systems, circuits and methods for improving data transmission by conditioning signals at a transmitter to compensate for channel effects.
2. Art Background
Electronic circuits utilize serial data transmission to transmit data among one or more circuits. In general, serial data transmission involves transmitting bits in a single bit stream at a predetermined data rate. The data rate is expressed as the number of bits transmitted per second (“bps”). Typically, to transfer data between circuits, the sending circuit employs a transmitter that modulates and sends data using a local clock. The local clock provides the timing for the bit rate. The receiving circuit employs a receiver to recover the data, and in some cases, the clock. The receiver circuit recovers the serial bit stream of data by sampling the bit stream at the specified data rate.
Some communication standards, which use optical channels to transfer data, demand high-speed data rates. For example, current standards transmit data across optical channels at 10 Giga bits per second (Gb/s). For example, two current standards for high-speed data transfer include the SFI specifications, associated with SFP+ optical modules, and the 10GBASE-KR specification from the IEEE for signaling over backplane channels in computer servers and networking equipment. For example, some standards, such as the SFI specification, require a transmitter to operate with a low transmitter waveform dispersion penalty (“TWDP”) and low data dependent jitter (“DDJ”) specifications at the same time. Prior techniques have been developed in an attempt to maximize the efficiency of serial data transfer at high rates. However, in some prior art design techniques, improving the TWDP cases a degradation of DDJ.
Accordingly, it is highly desirable to develop receiver and transmitter circuits that satisfy both standards such that improvements in TWDP does not cause degradation in DDJ.